This invention relates to a medical operation instrument for an endoscope (hereinafter referred to as "an endoscope operation instrument"), for example, forceps inserted into the coeliac cavity through an endoscope channel for medical operation.
The endoscope operation instrument, biopsic forceps, for example, is fitted at the proximal end with a control section containing a control slider and, at the distal end, with a medical operation cup connected to the control slider by means of a control wire. After the forceps are inserted into the endoscope forceps channel and the medical operation cup is drawn into the coeliac cavity, the cup is opened by pushing the control slider. Ordinarily, the control slider can be advanced further even after the cup is fully opened, the object being to enhance reliable opening of the cup even if the control wire itself, or the control wire channel is extended.
When, however, the operator earnestly surveys a section designated for biopsic observation (simply referred to as "a biopsic section") or considerable technique is demanded for the task of inserting the forceps into the internal organ in which said biopsic section is situated, it often happens that the operator unknowingly applies excessive force to the control slider. Also, when the tissue is sampled, the operator often tends to apply excessive force to the control slider in an attempt to completely open the cup for sampling of intact cells. When, as mentioned above, the control wire is forced excessively, namely, when the control slider is further pushed inward despite the full opening of the cup, the proximal end of the control wire, in particular, is subjected to an undue lengthwise compression. As a result, the strands constituting the control wire swell radially, presenting difficulties in effecting subtle handling of the medical operation section, what with the control wire failing to respond appropriately due to buckling or deformation.
To dissolve the above-described difficulties, a process has already been proposed which is characterized by enclosing the control wire in a tube. In this case, machining and fitting of the tube is required, leading to a higher instrument manufacturing cost. Further, the assembly of the control wire and enclosing tube constitutes too thick a mass to allow for ease of movement.